A one-step synthesis of novel high pH-sensitive nitrogen-doped yellow fluorescent carbon dots and their detection application in living cells†
Monitoring the pH in living cells is of great significance for a deeper understanding of cellular functions for effective disease diagnosis. Herein, a rare example of N-doped carbon dots (N-CDs) that emit bright-yellow fluorescence prepared using o-phenylenediamine as a carbon precursor via a simple one-pot hydrothermal method is reported. The as-prepared N-CDs exhibited not only highly optical stability and good biocompatibility but also pH sensitivity. A good linear relationship between the fluorescence intensity and the pH value could be obtained in the range of 4.2 to 7.0 (R2 = 0.9983). In addition, N-CDs also possess superior selectivity toward hydrogen ions over common metal ions and some bioactive molecules. On this basis, N-CDs are successfully applied to cellular imaging and to monitor pH fluctuations in living cells.